From Aesop's Fables:
A lion watched a fat bull feeding in a meadow, and his mouth watered when he thought of the royal feast he would make, but he did not dare to attack him, for he was afraid of his sharp horns. Hunger, however, presently compelled him to do something: and as the use of force did not promise success, he determined to resort to artifice. Going up to the bull in a friendly fashion, he said to him, "I cannot help saying how much I admire your magnificent figure. What a fine head! What powerful shoulders and thighs! But, my dear friend, what in the world makes you wear those ugly horns? You must find them as awkward as they are unsightly. Believe me, you would do much better without them." The bull was foolish enough to be persuaded by this flattery to have his horns cut off; and, having now lost his only means of defense, fell an easy prey to the lion.
Prior to making this comic, I had never considered the relation of the horns of a bull to its skull and much less how a rancher might remove the horns. The short answer is that he wouldn't. Although several methods make the removal of the horn "buttons" of a calf fairly easy, once the bull is an adult, trying to remove the horns would be very painful and carry a high risk of infection. As a result usually only the tips of the horns, which wouldn't cause these problems, would be removed, if anything at all.